My wife and I decided to dress up for the release of the Avengers movie earlier this year. Considering the fact that I had been growing my hair out and that I had a beard we thought it appropriate for me to go as Thor. I started by making Thor's hammer Mjolnir, which you can see here: How to Make the Hammer of Thor.
After I finished the hammer my wife helped me finish the rest of the costume. Unfortunately I didn't get a whole lot of pictures but I will try to fill the details in by explaining each step really well.
Step 1: Supplies
The chest piece was attached to a piece that I termed "the yoke" because I didn't know what else to call it. It was kind of like a huge collar. For that piece I used cardboard and black spray paint.
The cape was made from a red bed sheet. I recommend this because it's already nicely hemmed, and it's a pretty cheap way to buy several yards of fabric.
The wrist bands were made from scraps that I cut from the bed sheet and were held on using leather straps.
For the boots I made spats out of pleather and attached them to boots I already had.
For the rest I just wore blue jeans and a black muscle shirt.
The tools you'll need to do it the way I did it are a hot glue gun and plenty of glue sticks, a pair of scissors, a stapler, and a utility knife.
Step 2: Yoke and Cape
For this step I cut an oval (roughly) out of carboard and then cut the ends off. To give you an idea of the size, it needs to be about the width of your shoulders and the hole in the middle needs to be big enough for your head to fit through. That's really all that matters size-wise. After it was all cut out I just spray painted it black.
The black strip of cloth you see in the picture got added so that the cardboard stayed flat against my chest and back instead of sticking out like it kept wanting to do. It meant that I had to slip my arm through it as I slipped my head through the collar/yoke so that the strap went across my chest and under my arm. I just stapled it onto the cardboard.
To attach the cape I stapled the edges of each side at about the halfway point in the hole. Then I folded it into pleats and stapled each pleat down.
Step 3: Chest Plate and Belt
We couldn't find foam sheets big enough to do the whole thing so we pieced some sheets together. We just took come larger pieces and taped along the seams on the back. I also put hot glue in the seams by folding them back, putting glue into the seam and then "closing" the seam. Once we had our large piece of foam we cut out the design. We did try to keep the seams in places that wouldn't be too noticable.
The chest piece is done in five separate parts. The background piece, which we spray painted grey, the two strips that go up the middle, which we spray painted silver, and the two independent circles, which were also spray painted silver. I hot glued the pieces together and voila!
I hope I can correctly convey how I did the belt on here. I'll try to label the parts in the photo so it's clear which parts I'm talking about. It's made from two main identical parts. The top and bottom "straps" and the part that the circle is attached to (with the triangle pointing down) are one piece. I made two of those and then I connected them in the middle with two strips of foam. Then I put the four vertical strips on the back and added the circles. The circles are painted silver to match the other ones. To be completely honest I didn't paint the rest of the belt to match the chest plate because I ran out of paint and didn't have time to get more. I'm just glad I was using grey foam.
Step 4: Throwing It All Together
The rest of the costume was pretty much thrown together. Most depictions that I found of Thor seem to have him in blue pants, or at least dark pants. He's also frequently depicted in a black shirt. So I just decided to wear blue jeans and a black muscle shirt.
There a lot of different variations on the "vambraces" that he wears. Some of them just had a red band with a strap around it so I went with that one. I wrapped some excess fabric that I cut off the sheet around my arms and held them in place with some leather straps with buckles. The straps are from some leather vambraces I made, but you could just use a couple thin belts wrapped around a few times.
I already had the boots with straps around them. I simply cut out some pieces of pleather and inserted them into the straps so they would look like part of the boot. There are a lot of different ways to fake boots so if you can't do it this way don't worry. Some of the older style comic book art appears to have him wearing boots that look like they're just golden yellow fabric wrapped around his legs up to about his knees.
There are a lot of fun ways to do this costume, and I'd be excited to see your version. Whether you do it this way or not I hope you have fun becoming the God of Thunder!